Field of the Invention
The present invention relates to wireless communication. More particularly, the present invention relates to a method for transmitting data between wireless devices in a wireless communication system and an apparatus using the same.
Discussion of the Related Art
The next generation wireless communication system under active research aims a system capable of transmitting various kinds of information such as video and wireless data, being evolved from the initial system providing voice-oriented services. The fourth-generation wireless communication currently under development subsequent to the third-generation wireless communication aims to support high speed data transmission with 1 Gbps (gigabits per second) data rate in the downlink and 500 Mbps (megabits per second) in the uplink. The main objective of wireless communication system is to provide a plurality of users with reliable communication means independent of their location and mobility. However, any wireless communication channel always reveals non-ideal characteristics such as path loss, noise, fading due to multipath, inter-symbol interference (ISI), or Doppler Effect due to mobility of a terminal. Various technologies are under development to overcome non-ideal characteristics of wireless communication channels and improve reliability thereof.
Meanwhile, data capacity for cellular wireless systems is ever increasing according to the introduction of machine type communication (MTC) and the advent and deployment of various devices such as smart phones and tablet PCs. Various technologies are under development to meet the needs for high data capacity. For example, carrier aggregation (CA) technology and cognitive radio (CR) technology are good examples of an effort to utilize frequency bandwidth more efficiently. Also, multi-antenna technology, multi-base station collaboration technology, a direct communication system, etc. to increase data capacity within limited frequency bandwidth are being studied.
In direct communication system, user equipments (UEs) directly perform transmission and reception between themselves without relay of a base station. In a direct communication system, there is needed a method for acquiring transmission/reception timing and/or synchronization between the UEs for performing transmission and reception between the UEs, and a method for minimizing the interference that can occur during direct communication.